1. Field of the Invention
The present invention relates to a system for filtering dust particles from air and particularly to an improved system employing pulsed air in a reverse direction for more efficient cleaning of filter bags.
2. Description of the Prior Art
Present air filtering systems utilize a plurality of elongated filter bags supported vertically from a tube sheet within an enclosed housing. Dust-laden air is normally drawn into the lower housing and passed through the filters with clean air being exhausted from the open ends at the top. Removal of the dust collected on the outer surface of the filters is accomplished by periodically supplying pulses of compressed air through vertical pipes or horizontal blow tubes having holes spaced over the bag openings. The air is forced in a reverse direction through venturis in the open ends to dislodge the dirt on the outer surface of the bags. The dirt is then collected in hoppers at the bottom of the housing for mechanical removal. Selected groups of bags are cleaned together in a controlled sequence to permit continued operation. Examples of such known systems are found in U.S. Pat. No. 4,174,204, issued Nov. 13, 1979, and No. 3,963,467, issued June 15, 1976.
These systems generally have several disadvantages including the attraction of dust and dirt by bags adjacent to those being cleaned, frequent misalignment of blow tubes and pipes over the venturi openings of the bags due to bending or movement during installation, inspection, or repairs, and the need for removal of elements in order to permit bag replacement. Additional structural connections are also required for the tubes to minimize vibration caused by blasts of compressed air.